When fabrics are laundered, it is frequently desirable to treat them with fabric softeners, not only to soften them, but to give them greater bulk, make them easier to iron, decrease fabric drying time, and reduce static charge. A fabric softener that is commonly used in laundry detergents, rinses, and dryer sheets, such as the dryer sheets of U.S. Pat. No. 3,686,025 (Morton), is N-dihydrogenatedtallow-N,N-dimethylammonium chloride (DTMAC), which is both inexpensive and effective as a softener but, on the other hand, has certain deficiencies, such as its yellowing and reducing the washability of the softened fabrics, having inefficient antistatic activity on polyesters, and decreasing the rewettability of the treated fabrics.
Amine oxides are also known to be useful as fabric softeners, including softeners incorporated into laundry dryer sheets. When thus utilized, they have most commonly been employed as dilute aqueous solutions. However, copending application Ser. No. 07/591,214 (Corona et al.) discloses that the use of solid amine oxides instead of conventional dilute aqueous solutions in preparing the dryer sheets permits the elimination of a bothersome drying step and increases the loading of amine oxide that can be incorporated. The solid amine oxides which are used by Corona et al. are the mixed tert-amine oxides of copending application Ser. No. 07/591,425 (Borland et al.), i.e., tert-amine oxides containing at least one long-chain group and at least one short-chain group, in which at least some of the molecules are dihydrate molecules.